Index of /CTAN/macros/latex/contrib/linop

The linop package v0.1

Johannes Weytjens

johannes.weytjens@nietsissimpel.org June 6, 2016

Contents

1 Introduction

1

2 List of commands

2

3 List of options

2

4 Advanced control

4

1. Introduction

There exist already many packages to help you typeset common and less common mathematical notation with ease. Yet, to the best of my knowledge, there does not yet exist a package that provides an easy way to typeset operators as they appear for example in many body physics, quantum (field) theory or linear algebra. The aim of this package is to provide two simple commands and many options to easily write operators in any of the ways they commonly appear.

Besides providing easy to use macros, this package also ensures consistent spacing for subscript and superscript. To illustrate this point, compare the normal way for typesetting operators with the macros provided by this package.

\hat{a}_{in}\hat{a}_{in}^{\dagger}

ˆa_inˆa_in^†

\op{a}{in}\hc{a}{in}

ˆa_inˆa_in^†

Typesetting the

\dagger

and a subscript simultaneously pushes the subscript down, this is no longer the case with the here defined macros.

1.1. Required packages

As these are simple macros, you only need the

xparse

_package.

1

2. List of commands

The two macros defined in this package are

\op

and

\hc

as well as their starred versions.

\op[

superscript spacing

]{

operator

}{

subscript

}{

superscript

}{

supersuperscript

}

\hc[

superscript spacing

]{

operator

}{

subscript

}{

superscript

}{

supersuperscript

}

These macros typeset an operator and the Hermitian conjugate respectively. Only the operator argument is mandatory, all other arguments can either be empty or be skipped entirely if no subscript or superscript is desired. The optional argumentsuperscript spacingonly applies to the starred versions.

Supersuperscripts are implemented to distinguish between e.g. the order in some expansion and the square of the operator.

\op{a}{in}{0}

aˆ⁰_in

\op{a}{}{(1)}{2}

aˆ⁽¹⁾²

\hc{b}{out}{0}

^ˆb^†0_out

\hc{b}{out}{}{2}

^ˆb^†_out²

The defaults style is to typeset all operators with a hat. The none starred versions use

\hat

and are only appropriate for single symbol operators. The starred version use

\widehat

which scales with the width of the operator and can therefore be used for wider symbols. The

\widehat

often overlaps with the superscripts however, so the starred version insert a

\>

before the superscripts and a

\:

_for the Hermitian conjugate superscript. Controling the spacing of the superscript for individual operators can be done with the optionalsuperscript spacingargument.

\op*{A}{in}{0}

Ab_in⁰

\hc*{ab}{out}

a bc_out^†

\hc*[\kern4pt]{\mathcal{L}}

Lc^†

3. List of options

3.1. bold

Some prefer to use bold letters for operators instead of hats. This can be achieved by using the

bold

option when loading the package. When using this option, the starred versions will produce the same result as the none starred versions.

\op{a}{in}{0}

a⁰_in

\hc{b}{out}

b^†_out

3.2. bmbold

The

bmbold

option achieves the same effect as bold, but instead uses the bold math font provided by the

bm

package.

2

\op{a}{in}{0}

a⁰_in

\hc{b}{out}

b^†_out

3.3. nohat

The option

nohat

typesets the operators without a

\hat

. This also applies to the starred versions.

\op{a}{in}{0}

a⁰_in

\hc{b}{out}

b^†_out

3.4. wide

With the wide option, all operators will use

\widehat

, regardless of whether you’re using the starred or non starred versions.

3.5. star

The

star

options typesets the Hermitian conjugate with a star instead of a dagger.

\hc{b}{out}

^ˆb^∗_out

3.6. compact

The consistent spacing is provided by using

\mathstrut

in both the subscript and superscript. As the misalignment is caused by using a

\dagger

in the superscript, the same effect can be achieved by using a

\phantom{\dagger}

in the superscript of the non Hermitian conjugated operator. This turns out to be slightly more compact than using

\mathstrut

, though the effect is minimal¹.

\op{a}{in}\hc{a}{in}

ˆa_inˆa_in^† using

\mathstrut

\op{a}{in}\hc{a}{in}

ˆa_inˆa_in^† using

\phantom{\dagger}

Figure 1

Illustrating the difference between\mathstrutand\phantom{\dagger}. The light grey letters are the compact version that used\phantom{\dagger}_.

1 This is because\mathstrutis defined as\def\mathstrut{\vphantom(}and(turns out be slightly larger than

\dagger_.

3

3.7. square

To help distinguish between the operator and the indices, the subscript and superscripts can be given in square brackets as well when using the

square

_option.

\op{a}[in][0]

ˆa⁰_in

\hc{b}[out]

^ˆb^†_out

4. Advanced control

All the options above are set by renewing some custom commands which are

command default value description

\linopstyle \hat

style of operators

\linopstylewide \widehat

style of starred operators

\linopconjugate \dagger

symbol used for Hermitian conjugate

\linopspacewide \>

spacing in superscript of

op*

\linopspacewidehc \:

spacing in superscript of

hc*

\linopsubscript \mathstrut

equal spacing in subscript

\linopsuperscript \mathstrut

equal spacing in superscript of

op

\linopsuperscripthc \mathstrut

equal spacing in superscript of

hc

These can be changed with

\renewcommand

for even further control.

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